Published in:
01-09-2011 | Original Article
Molecular imaging with 68Ga-SSTR PET/CT and correlation to immunohistochemistry of somatostatin receptors in neuroendocrine tumours
Authors:
Daniel Kaemmerer, Luisa Peter, Amelie Lupp, Stefan Schulz, Jörg Sänger, Vikas Prasad, Harshad Kulkarni, Sven-Petter Haugvik, Merten Hommann, Richard Paul Baum
Published in:
European Journal of Nuclear Medicine and Molecular Imaging
|
Issue 9/2011
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Abstract
Purpose
Somatostatin receptors (SSTR) are known for an overexpression in gastroenteropancreatic neuroendocrine tumours (GEP-NET). The aim of the present study was to find out if the receptor density predicted by the semi-quantitative parameters generated from the static positron emission tomography (PET/CT) correlated with the in vitro immunohistochemistry using a novel rabbit monoclonal anti-SSTR2A antibody (clone UMB-1) for specific SSTR2A immunohistochemistry and polyclonal antibodies for SSTR1 and 3–5.
Methods
Overall 14 surgical specimens generated from 34 histologically documented GEP-NET patients were correlated with the preoperative 68Ga-DOTA-NOC PET/CT. Quantitative assessment of the receptor density was done using the immunoreactive score (IRS) of Remmele and Stegner; the additional 4-point IRS classification for immunohistochemistry and standardized uptake values (SUVmax and SUVmean) were used for PET/CT.
Results
The IRS for SSTR2A and SSTR5 correlated highly significant with the SUVmax on the PET/CT (p < 0.001; p < 0.05) and the IRS for SSTR2A with the SUVmean (p < 0.013). The level of SSTR2A score correlated significantly with chromogranin A staining and indirectly to the tumour grading.
Conclusion
The highly significant correlation between SSTR2A and SSTR5 and the SUVmax on the 68Ga-DOTA-NOC PET/CT scans is concordant with the affinity profile of 68Ga-DOTA-NOC to the SSTR subtypes and demonstrates the excellent qualification of somatostatin analogues in the diagnostics of NET. This study correlating somatostatin receptor imaging using 68Ga-DOTA-NOC PET/CT with immunohistochemically analysed SSTR also underlines the approval of therapy using somatostatin analogues, follow-up imaging as well as radionuclide therapy.